July 10, 2013. Problems with how the brain assigns importance to learning may contribute to psychosis, according to a study published online June 4 in the American Journal of Psychiatry. The results support the idea that faulty learning in the brain can give rise to the delusional beliefs of schizophrenia. For example, if the brain incorrectly flags something as important or valuable, this could lead to bizarre beliefs, such as hearing voices in radio static.

Senior author Graham Murray and first author Javier Bernacer of the University of Cambridge, United Kingdom, caused mild psychosis symptoms in healthy volunteers by using a low dose of methamphetamine. Brain scanning revealed lowered brain activity in the ventromedial prefrontal cortex, a region that endows value to something perceived. The more psychotic symptoms a subject experienced, the lower the activity, suggesting that the two are linked. This implies that brain chemicals can sufficiently alter the messages flowing between brain cells so as to tilt the brain toward the scrambled thinking in psychosis. (For more details on this, see our news story.)—Michele Solis.